Here's a better question: Why should or shouldn't someone care about image, and why?

One explanation is that perhaps evolutionarily speaking, it would be advantageous for human beings to care about image than those who don't, and hence those who care about image will be selected over those who don't.

Second explanation is that Fe valuers care about image.

So you have two rival explanations, and I would argue that the first evolutionary explanation is the better explanation. And you would argue, but why?

The reason is because what the Socionics explanation is merely saying is that "I have observed that there are people who care about image, and these people will always continue to care about image in the future". It's saying that a certain pattern will continue merely because that's what has been observed in the past.

The evolutionary explanation will say that that much is obvious, but why? Why should that pattern continue? What possible reason is there to assume such a thing? And the reason is because it has been evolutionarily selected over a long period of time. Sure this trend could change in the future, but not anytime soon. So there's a good reason to believe that this trend will continue into the foreseeable future.

What the Socionics explanation is saying is obvious enough, but the evolutionary explanation will say that, and then some.